(06-26-2014, 03:14 PM)retired_guy Wrote: Wow Sleepy, your pressure sure stays on the top, doesn't it?
Your apnea's are obstructive for the most part, not central. So that I think is good.
So the question is why do you need such a top end pressure?
One of three things is likely happening:
1) You really do need more pressure than the max of 20cm to keep your airway open during (presumably) supine or REM or supine-REM sleep, and your current machine can't deliver that much pressure. In which case you need to either learn to stay off back or you need to talk to your sleep doc about being switched to a bi-level that can go up to 25cm if necessary.
2) Your min pressure is not set high enough and once the events start happening on a bad night, the rapid increase in pressure (9cm in 10-12 minutes) does not allow the airway to have a chance to stabilize. And the unstable airway leads to additional events being scored and the machine becomes very reluctant to reduce the pressure. You can test this hypothesis by increasing the min pressure to something a lot closer to 20. But I'd also advise you not to make the change in min pressure in one big jump. But it may very well be worth increasing the min pressure by 1-2cm and leave it there for 3-4 days before increasing the min pressure again. The goal is to find the lowest min pressure that prevents most of your events from happening in the first place so that the machine is not so prone to quickly jacking up the pressure when the events start.
3) Those aren't OAs at all, but rather they're mis-scored CAs. The Resmed FOT algorithm for detecting CAs is not infallible, and as the pressure goes up, the chances that a CA will be mis-scored as an OA also increase. In this case, that drastic 9cm jump in pressure that occurs in about 10-12 minutes may be triggering a CO2 overshoot/undershoot cycle, but because of the high pressure, the FOT mis-scores the CAs as OAs. And, of course, the fact that the machine is scoring them as OAs means the machine is less likely to reduce the pressure and let the breathing stablize. If this is what's happening on the bad nights, then you really need to get the sleep doc involved in figuring out where to go from here. A change in the APAP range might help; or not. A change to bi-level might help; or not.
In my opinion, it's worth consulting your sleep doc and showing him the data and asking him for his opinion about whether a bi-level is called for.